Porous and non-porous particle reinforcement for viscous hydraulic matrices

ABSTRACT

A hydraulically-applied mulch matrix comprising non-porous particles, porous particles and mixtures thereof combined with a mechanically and or chemically bonded fiber mulch mixed within a high viscosity slurry to keep the particles in suspension for dispersion onto soil surfaces with mulch spraying equipment for enhanced erosion control and higher level plant establishment.

This application is a continuation-in-part of U.S. application Ser. No.12/036,417 filed Feb. 25, 2008, now U.S. Pat. No. 7,752,804, issued Jul.13, 2010, which, in turn, claims the benefit of U.S. provisionalApplication No. 60/891,570 filed Feb. 26, 2007, now expired. Thedisclosures of which are incorporated in their entirety by referenceherein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to highly viscous hydraulically-applied mulchmedia containing porous particles to enhance erosion control andvegetation establishment performance of the mulch matrix for applicationto soil and soil-like surfaces.

2. Background Art

The purpose of mulches is to increase seed germination and decrease soilerosion to allow seedlings to become firmly established in the soil.Mulches typically consist of natural materials such as straw, hay, wood,paper or compost. The mulches are generally mixed with water and placedin a holding tank where they are mixed and then sprayed onto the desiredsoil surface. Reference is made to the sprayable mulch of Hansford, U.S.Pat. No. 4,297,810 entitled “sprayable hydromulch”, which is comprisedof hay, magazine paper stock, a binder and a coloring agent.

These chemically bonded natural fiber hydraulically-applied mulches mayrely upon soil chemistry or positive-negative attraction modes to securethe soil surface for short term erosion control. Mechanically and/orchemically bonded fiber matrices rely upon physical, fiber to fiberand/or chemical bonding for erosion control performance. Although themulches may be sufficiently well bonded, erosion control and plantestablishment performance has been limited for a number of reasons. Insome instances the chemically-bonded mulch forms an almost impenetrablelayer over the soil surface that limits water and oxygen needed forplant growth. Additionally, the mulch layer itself can be difficult topenetrate by germinated seedlings Mulch matrices which lack mechanicallyinterlocking fibers have difficulty absorbing raindrop splash energy,are susceptible to sheet erosion and cannot withstand prolongedconcentrated flow energy.

Crimped natural fibers or man-made fibers comprised of polyester,polypropylene, cellulose, and other natural and man-made polymers havebeen linked to form a matrix, which allows penetration by germinatedseedlings and allow air, water and light to reach to the soil surface.However, these synthetic fibers are not readily biodegradable and thenatural fibers, though biodegradable, do not retain the matrix formationrequired to handle high rates of concentrated flow energy associatedwith rilling erosion. Rill erosion is the removal of soil byconcentrated water running through streamlets. This level of erosiveenergy is commonly associated with long slope length or areas ofoverland flow.

SUMMARY OF THE INVENTION

The present invention provides a composition for viscous hydraulic mulchmatrices featuring porous or non-porous particles mixed with amechanically and or chemically bonded fiber mulches in a highly viscousslurry. The porous particles contain internal channels and spaces whichincrease the flow of water and oxygen through the mulch matrix andprevent loss of water by retaining moisture longer in the micro-poreinterstitial spaces. It is further the object of this invention toprovide methods of preparation of the sprayable mulch matrix within ahydraulic seeding machine or by combining the porous ceramic particlesduring the production of the mulch medium or the chemical binder that iscombined with the mulch. The mechanically and or chemically bonded fibermulch is mixed with a sufficient amount of porous particles. A preferredembodiment utilizes a porous ceramic particle. However particlescomprised of perlite, vermiculite, zeolite, Fuller's earth, diatomatiousearth, clay and/or crushed aggregates or mixtures thereof, may also beutilized.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

The invention thus features particle reinforced sprayable mulch forapplication to soil surfaces in a number of commercial markets,including gardening, grounds maintenance, landscaping, highway roadsideconstruction and maintenance, landfills, mining, slope stabilization,turf reinforcement systems, roof greening, and agriculture, to name afew. In addition the mulch product may also contain natural binders,traditional organic and inorganic mulch fibers, soil amendmentsincluding fertilizers, compost, herbicides, and pesticides, and whenappropriate, seeds, stolons and other forms of live plant materials.

The mulch fibers composition may comprise 75-98% by weight of mulch. Theratio of mulch fibers to chemical binder is 7 to 30:1 or preferably 10:1in the final composition. Water is added to the mixture to form thehydraulic slurry prior to introducing the porous ceramic particles. Themulch, comprised of crimped fibers, non-crimped fibers, or a mixturethereof, is used to prepare a mechanically and or chemically bondedfiber mulch matrix. The fibers may be man-made fibers, or naturallyoccurring fibers, for example. Natural fibers are preferred and mayinclude wood, straw, coir and jute fibers, cotton, flax, paper, compostor a mixture thereof. The mechanically bonded mulch fibers are describedin Spittle, U.S. Pat. Nos. 5,741,832; 5,779,782; 5,942,029; 6,349,499;and 6,360,478, which are incorporated herein by reference.

The average fiber length should be at least ⅛ inch (3.175 mm), andpreferably at least 3/16 inch (4.762 mm) Selection of fibers formanufacturing may be enhanced by a rotap classifier utilizing, 8, 16,24, 50 and 100 mesh sieves retaining a minium of 30% or more of thescreened fibers on the 8, 16 & 24 combined sieve collection. The fibersselected should be treated, preferably with a polymer-based waterabsorbent, added to the fiber mulch to establish the high viscosityrequired to suspend the porous ceramic particles within the matrix.Suspending polymer agents such as guar gum, pectin, gelatin,carrageenan, psyllium, chitosan, bean mills, polyacrylamides and/orsodium polyacrylate at a quantity required to preferably achieve aminimum slurry viscosity of 1,000,000 centipoises, when evaluated by aSST2000 Rheometer with vane V4-20 at 22 degrees C. Additional methods offiber selection are presented in Spittle, U.S. Pat. Nos. 6,076,299 and6,158,167, which are incorporated by reference herein.

In order to facilitate suspension of the mulch and porous particles forspraying purposes, the mulch matrix and porous ceramic particles may besuspended in a highly viscous slurry with a consistency of pudding. Thehigh viscosity slurry may be comprised of fibers with a crosslinked ornon-crosslinked hydrocolloid binder. Although a crosslinked hydrocolloidbinder such as an agar, carrageenan, gelatin, pectin or guar gum is thepreferred slurry ingredient, other slurry ingredients such aspolyacrylamide, sodium polyacrylate, psyllium, chitosans, starches, beanmills and mixtures thereof may be used as suspending agents and binders.Additional suspending agents are well known to those skilled in the art,and include, without limitation, associative thickeners, water solublepolymers of numerous types, naturally occurring saccharide-basedpolymers such as starches and soluble lignocellulosic digestionproducts, and proteins. Chemically derivatized celluloses are alsouseful, examples being methyl cellulose, propyl cellulose, hydroxymethylcellulose, hydroxypropyl cellulose, carboxymethyl cellulose and thelike.

Associative thickeners are molecules of moderate to low molecularweight, generally below 25,000 Da and more preferably lower than 20,000Da which, in an aqueous environment, associate through overlap ofhydrophobic and hydrophilic segments, creating massive associatedspecies in solution. Examples of such associative thickeners arepolymers with a polyoxyethylene internal hydrophile and externalhydrophobes. Such associative thickeners can be prepared, for example,by oxyethylating ethylene glycol to a desired molecular weight, followedby oxyalkylating with a long chain α-olefin oxide. The long chain alkylgroup preferably has from 8 to 30 carbon atoms. The associativethickeners with longer chain alkyl groups are particularly shearsensitive, so their dispersions can be easily pumped and sprayed, yetreversibly increase viscosity dramatically upon storing. The amounts ofsuch suspending agents can be preferably less than 15%, but in any casesufficient to achieve the desired viscosity. Amounts as little as 1-2%are effective. Associative thickeners of higher biodegradability can befabricated by utilizing “natural” hydrophiles and hydrophobes, forexample hydrolyzed celluloses or polysaccharides, and polylactic acid,polyglycolic acid, and poly(lactic/glycolic) acid copolymers.

The particles may be added to the fiber mulch during manufacture orprior to dispensing of the fiber and slurry composition from mulchspraying equipment. Likewise, the addition of soil amendments such asfertilizer, compost, herbicides, pesticides and when appropriate, seeds,stolons and other forms of live plant material may be added during thefiber mulch preparation or prior to dispensing of the fiber and slurrycomposition from mulch spraying equipment. The combination of porousceramic particles with the mechanically and/or chemically modified fibermulch matrix facilitates use of natural fibers to create a highlyeffective resultant mulch product. These enhanced formulations retainthe matrix properties to preserve vertical movement of water and oxygenwhile increasing the density of the fiber matrix allowing for higherrates of kinetic energy (force) absorption of large diameter raindropsfalling at terminal velocity from intense storms and resulting overlandflow (shear stress) over long slope surfaces or in areas of concentratedflow such as drainage ditches, channels and shorelines.

The enhanced fiber mulch formulations may be used in combination withnon-degradable turf reinforcement mats and other geosynthetic orstructural systems used to reinforce natural vegetation. When fullyvegetated, these systems are capable of doubling the erosion resistanceof natural vegetation versus un-reinforced vegetation. The enhancedfiber mulch formulations may be applied below, within or above thegeosynthetic component resulting in increased short-term erosionprotection (prior to and during growth establishment) and acceleratedgrowth establishment and density of the vegetation for permanentlong-term protection. Turf reinforcement mats disclosed in Spittle, U.S.Pat. No. 6,729,807, and Theisen, U.S. Pat. Nos. 5,616,399 and 5,567,087,are incorporated by reference herein.

The preferred porous particle is a porous ceramic particle which isclay-based and marketed by Profile Products, LLC of Buffalo Grove, Ill.These porous ceramic particles are an inorganic soil treatment developedto preserve water and oxygen flow to plant root systems in easilycompacted soils. The porous ceramic particles should be of sufficientlysmall size to facilitate combination and use in a viscous hydraulicmulch matrix. In development of the sprayable hydraulic mulch productthe smaller the porous particle size, the better retention of moistureand distribution throughout the fiber mulch matrix.

The final concentration should provide from one million particles to 50million particles per pound (2.2 million particles to 110 millionparticles per kilogram). The final concentration may be determined bythe desired moisture retention and erosion control performance requiredfor the target soil surface, slope gradient, slope length, annualrainfall rate and the anticipated storm intensity run off conditions.

While porous ceramic particles are the preferred slurry ingredient toincrease the density and pore space of the fiber matrix, theincorporation of other particles such as perlite, vermiculite, zeolite,Fuller's earth, diatomatious earth, clay or mixtures and/or crushedaggregates thereof, will facilitate a comparable performance responserelative to enhancing erosion control and vegetative establishment ofthe hydraulically-applied mulch matrix. Numerous smectite clays are alsofeasible for use in forming porous particles. Those containingsignificant quantities of montmorillinite and opal CT (cristobalite,tridymite) are preferred. Other particularly suitable clays are thesmectite clays such as bentonite, montmorillinite (preferred),beidellite, nontronite, hectorite, saponite, attapulgite, sepiolite andmixtures thereof. Suitable porous calcined smectite clay soil amendmentsare disclosed in Tanner, et al, U.S. Pat. No. 6,358,312 entitled “SportsField Soil Conditioner,” incorporated herein by reference.

The introduction of the porous ceramic particles within the hydraulicfiber mulch requires a highly viscous slurry, whose viscosity isdependent upon the physical properties of the particles, for exampletheir size, density, and morphology. The viscosity is adjusted so as tobe able to maintain the particles in suspension such that a uniformmixture can be sprayed. This viscosity is preferably a minimum of1,000,000 centipoises when evaluated by an SST2000 Rheometer with vaneV4-20 at 22 degrees C. which facilitates the retention of the particleswithin a viscous hydraulic mulch matrix when applied with standard mulchspraying equipment. However, in some cases, the viscosity may be lower,for example 500,000 cps or 300,000 cps. In the quiescent state (no orvery low shear), the viscosity may reach very high values. However, theviscosity under shear should be low enough that the composition remainssprayable.

The incorporation of a high density particle such as sand with little orno pore space contribution will also enhance the erosion controlperformance of the applied hydraulic slurry by increasing the density ofthe installed fiber matrix, allowing for this matrix to absorb the raindrop energy more efficiently than if the particles weren't includedwithin the matrix.

The final composition of porous particles, the mulch matrix and the highviscosity slurry should enable the sprayable mulch to be dispersed at aconcentration range of approximately 15-98 kg/100 m². The density of thematrix has direct relationship to erosion control performance, whereinthe higher the density or weight per unit area, the greater the raindropsplash and erosive water energy dissipation.

The ratio of mulch solids, i.e. natural and synthetic fibers toinorganic particles is preferably in the range of 1:10 to 10:1, morepreferably 1:5 to 5:1, yet more preferably 1:3 to 3:1, still morepreferably 1:2 to 2:1, and most preferably about 1:1.

In one or more embodiments, there is provided a mulch including at leastone inorganic particle, at least one biodegradable manmade fiber, and asuspending agent. The at least one inorganic particle may include porousinorganic particles, non-porous inorganic particles, or mixturesthereof. The mulch may be mixed with water to form a viscous mulch forhydraulic applications. In certain instances, the mulch may furtherinclude at least one porous inorganic particle such as porous ceramicparticle described herein.

In certain instances, the at least one non-porous inorganic particle,the at least one porous inorganic particle, or a mixture thereof ispresent in 0.1 percent to 20 percent, 1 percent to 15 percent by weight,1 percent to 10 percent by weight, or 3 percent to 7 percent by weightof the total dry solids of the mulch.

In certain instances, the at least one biodegradable manmade fiberincludes one or more manmade biodegradable polymers. Without beinglimited to any particular theory, biodegradation can be accomplished bysynthesizing polymers with hydrolytically unstable linkages in thepolymer backbond. This can be achieved by the use of chemical functionalgroups such as esters, anhydrides, orthoesters and amides. Somebiodegradable polymers can be synthesized by ring openingpolymerization. Non-limiting examples of the manmade biodegradablepolymers includes polyglycolic acid, polylactic acid (PLA),polyhydroxyalkanoate (PHA), rayon, acetate, and any combination thereof.In certain particular instances, the manmade biodegradable fiber ispresent in 0.1 percent to 15 percent, 1 percent to 10 percent by weight,or 3 percent to 7 percent by weight of the total dry solids of themulch.

Non-limiting examples for the non-degradable manmade fibers include oneor more types of polyester such as polycaprolactone (PCL), polyethyleneadipate, polyhydroxyalkanoate (PHA), polyethylene terephtalate (PET),polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT),polyethylene naphthalate (PEN), and Vetran; one or more types ofpolyethylene; and one or more types of polypropylene. Certain particularexamples of the non-degradable manmade fibers may include Nylon,Modacrylic, Olefin, Acrylic, Vinyon, Saran, Spandex, Vinalon, andArmids.

In certain instances, the mulch may further include at least one naturalfiber, at least one non-biodegradable manmade fiber, or any combinationthereof. In certain particular instances, the at least one biodegradablemanmade fiber, the at least one natural fiber, and/or the at least onenon-biodegradable manmade fiber are present in 65 percent to 99 percentby weight, 70 percent to 95 percent by weight, or 80 percent to 90percent by weight of the dry solids of the mulch. In certain particularinstances, the at least one nature fiber is present in 65 percent to 99percent by weight, 70 percent to 95 percent by weight, or 80 percent to90 percent by weight of the dry solids of the mulch.

In certain instances, the at least one suspending agent includes apolyoxyethylene polyether, a polyacrylamide, a sodium polyacrylate,psyllium, chitosan, starch, bean mills, a polysaccharide, a methylcellulose, propyl cellulose, hydroxymethyl cellulose, hydroxypropylcellulose, carboxymethyl cellulose, or mixtures thereof. In certainparticular instances, the at least one suspending agent includes apolysaccharide. In certain other particular instances, the at leastsuspending agent is present in 2.5 percent to 17.5 percent by weight, 5percent to 15 percent by weight, or 7.5 percent to 12.5 percent byweight of the total dry solids of the mulch.

In one or more embodiments, there is provided a method for stabilizing asoil surface. The method includes applying to the soil surface a mulchdescribed herein. In certain instances, the at least one biodegradablefiber, the at least one suspending agent, and optionally the at leastone natural fiber and/or the at least one non-biodegradable fiber may bemixed with water to form a water mixture and thereafter the at least oneporous inorganic particle is added to and mixed with the water mixtureto form the hydraulically-applied mulch. Alternatively, all dry solidsincluding the fiber, the suspending agent, and the particles can befirst mixed to form a dry mixture and thereafter water is added to andmixed with the dry mixture to form a hydraulically-applied viscousmulch.

In order to determine the amount of erosion control provided by theembodiments of the invention, use of the enhanced fiber mulchformulations were tested with and without porous ceramic reinforcementImprovements in slope length stabilization, shear stress testing, wettensile strength and water retention. Two studies, slope and shearstress testing were performed at Utah State Water Research Laboratory,utilizing their rainfall simulator and channel testing flume. Rainfalltesting utilizing;

1. 4 feet plot width 2. 19.5 feet plot slope width 3. 2.5:1(horizontal:vertical) plot slope 4. Sandy loam soil type 5. 5.0 and 7.15inches per hour rainfall intensity 6. 1 hour testing duration 7. Shearstress testingThe Slope Length Benefit was calculated for the fiber mulch formulation,with a reinforcement particles, was found to have a cover managementfactor at 7.15 inches per hour of 0.0049. The cover management factorfor the fiber mulch formulation without reinforcement particles at 5″per hour, was 0.0004. Providing evidence that the fiber mulchformulation in combination with reinforcement particles improves covermanagement by at least 85%. In addition, slope length stabilization wascalculated using Rusle, and the fiber mulch formulation in combinationwith porous ceramic particle reinforcement can increase the slope lengthstabilization by a factor of 1.85. For example, if an FGM matrice canstabilize a 100 ft. long slope, then an FGM matrice reinforced withporous ceramic particles can extend the slope length protection to 185ft. without the need of an energy interrupter device.

Shear testing, wet tensile strength and water retention were alsoperformed on the fiber mulch formulation. The Bonded Fiber Matrix (BFM)mulch formulation, reinforced with porous ceramic particles infilledwithin a Turf Reinforcement Matrix (TRM) was found to have shearcapability of 2.5 lbs/sq ft. (test 1) and 106.9% improvement versus aBFM and TRM that had not been reinforced with porous ceramic particles.A wet tensile strength under 4″×5″ of water averaged 1.96 lbs wascalculated for the BFM with reinforcement particles formulation, whichwas a 98% improvement over the test material without reinforcingparticles for the BFM. Water retention was calculated as 69.35 grams forthe cured Flexible Growth Medium (FGM) matrix with reinforcementparticles for a 26.225 square inch area, an improvement of 10.5% versusan unreinforced FGM matrix.

The mulch applied in this test contained a 1:1 ratio of fiber mulch toceramic particles, and was spray applied at a rate of 7000 lbs/acre. Theamount applied can be considerably less, depending upon the particularapplication, topography, etc., for example 2000 lbs/acre, and can alsobe more, for example 10,000 lbs/acre.

While an embodiment of the invention has been described, it is notintended that the embodiment describes all possible forms of theinvention. Rather, the words used in the specification are words ofdescription rather than limitation, and it is understood that variouschanges may be made without departing from the spirit and scope of theinvention.

1. A mulch comprising: at least one inorganic particle; at least onebiodegradable manmade fiber; and a suspending agent.
 2. The mulch ofclaim 1, further comprising water to form a viscous mulch for hydraulicapplication.
 3. The mulch of claim 1, wherein the at least one inorganicparticle includes smectite clay, perlite, vermiculite, zeolite, Fuller'searth, diatomatious earth, or mixtures thereof.
 4. The mulch of claim 3,wherein the smectite clay includes bentonite, beidellite,montmorillinite, nontronite, hectorite, saponite, attapulgite,sepiolite, or mixtures thereof.
 5. The mulch of claim 1, wherein the atleast one inorganic particle is present in 0.1 percent to 20 percent byweight.
 6. The mulch of claim 1, wherein the at least one biodegradablemanmade fiber includes crimped biodegradable manmade fibers, non-crimpedbiodegradable manmade fibers, or mixtures thereof.
 7. The mulch of claim1, wherein the at least one biodegradable manmade fiber includespolyglycolic acid, polylactic acid (PLA), polyhydroxyalkanoate (PHA),rayon, cellulose acetate, or mixtures thereof.
 8. The mulch of claim 1,wherein the at least one biodegradable manmade fiber is present in 0.1percent to 15 percent by weight.
 9. The mulch of claim 1, furthercomprising at least one natural fiber.
 10. The mulch of claim 9, whereinthe at least one natural fiber is present in 65 percent to 99 percent byweight.
 11. The mulch of claim 9, wherein the at least one natural fiberis derived from wood, straw, cotton, flax, paper, coir, jute, compost,or mixtures thereof.
 12. The mulch of claim 1, further comprising anon-biodegradable manmade fiber.
 13. The mulch of claim 12, wherein thenon-biodegradable manmade fiber includes polyester fiber, polyethylene,polypropylene fiber, or mixtures thereof.
 14. The mulch of claim 1,further comprising at least one porous ceramic particle.
 15. The mulchof claim 1, having a viscosity of 300,000 centiposes or more.
 16. Themulch of claim 1, having a viscosity of 500,000 centiposes or more. 17.The mulch of claim 1, having a viscosity of 1,000,000 centiposes ormore.
 18. The mulch of claim 1, wherein the at least one suspendingagent includes a polysaccharide, a crosslinked hydrocolloid binder, anon-crosslinked hydrocolloid binder, or mixtures thereof.
 19. The mulchof claim 18, wherein the crosslinked hydrocolloid binder includes agar,carrageenan, gelatin, pectin, guar gum, or mixtures thereof.
 20. Themulch of claim 1, wherein the suspending agent includes apolyoxyethylene polyether, a polyacrylamide, a sodium polyacrylate,psyllium, chitosan, starch, bean mills, a polysaccharide, a methylcellulose, propyl cellulose, hydroxymethyl cellulose, hydroxypropylcellulose, carboxymethyl cellulose, or mixtures thereof.
 21. The mulchof claim 1, wherein the at least suspending agent is present in 5percent to 15 percent by weight.
 22. A mulch comprising: at least oneporous ceramic particle; at least one biodegradable manmade fiber; and asuspending agent.
 23. The mulch of claim 22, further comprising water toform a viscous mulch for hydraulic application.
 24. The mulch of claim23, wherein the at least one biodegradable manmade fiber includespolyglycolic acid, polylactic acid (PLA), polyhydroxyalkanoate (PHA),rayon, cellulose acetate, or mixtures thereof.
 25. A method ofstabilizing a soil surface, comprising applying to the soil surface amulch of claim
 1. 26. The method of claim 25, wherein the step ofapplying includes forming a water mixture of the at least onebiodegradable manmade fiber and the suspending agent with water andthereafter adding to the water mixture the at least one inorganicparticle.
 27. The method of claim 25, wherein the step of applyingincludes forming a dry mixture of the at least biodegradable manmadefiber, the at least one suspending agent, and the inorganic particle,and thereafter adding water to the dry mixture to form a wet mixture.